Rotary piston internal combustion engine with unitary or multi-partite sealing bar

ABSTRACT

A rotary piston internal combustion engine with a housing consisting of lateral parts and of a casing, and with a piston that is provided with several piston grooves extending parallel to the axis over the entire piston width; a radial seal in the form of a unitary or multipartite sealing bar is inserted into each groove so as to be radially movable whereby at least two sealing bars arranged in the piston differ from one another as regards their construction and/or materials used in connection therewith.

United States Patent [191 Lamm et al.

[451 May 27, 1975 ROTARY PISTON INTERNAL COMBUSTION ENGINE WITI-I UNITARY OR MULTI-PARTITE SEALING BAR [75] Inventors: Heinz Lamm, Esslingen-St.

Bernhardt; Lothar Kortner, Stuttgart, both of Germany [73] Assignee: Daimler-Benz Aktiengesellschaft,

Germany [22] Filed: Mar. 6, 1972 [21] Appl. No.: 232,000

3,253,581 5/1966 Nallinger 418/113 3,263,912 8/1966 Frenzel 418/121 3,268,157 8/1966 Frenzel 418/121 3,280,801 10/1966 Scherenberg 418/ 122 3,281,064 10/1966 Springer 418/120 3,400,691 9/1968 Jones 418/121 3,556,695 1/1971 Yamamoto 418/121 3,667,877 6/1972 Lamm 418/121 FOREIGN PATENTS OR APPLICATIONS 1,231,054 12/1966 Germany 418/122 Primary Examiner lohn J. Vrablik Attorney, Agent, or FirmCraig & Antonelli [57] ABSTRACT A rotary piston internal combustion engine with a housing consisting of lateral parts and of a casing, and with a piston that is provided with several piston grooves extending parallel to the axis over the entire piston width; a radial seal in the form of a unitary or multipartite sealing bar is inserted into each groove so as to be radially movable whereby at least two sealing bars arranged in the piston differ from one another as regards their construction and/or materials used in connection therewith.

7 Claims, 10 Drawing Figures ROTARY PISTON INTERNAL COMBUSTION ENGINE WITH UNITARY OR MULTI-PARTITE SEALING BAR The present invention relates to a rotary piston internal combustion engine with a housing consisting of lateral parts and of a casing and with a piston that is provided with grooves extending parallel to the axis over the entire piston width, in which a radial seal in the form of one or several unitary or multi-partite sealing bars are inserted in a radially movable manner.

I-Ieretofore, radial sealing bars of identical constructions were installed into each of the grooves at the corners of a polygonal piston. This entails the disadvantage that, for example, with the application of a unitary sealing bar the lateral gas tightness does not satisfy the present day requirements, especially when the engine is in the cold condition and/or rotates at small rotational speeds. Additionally, such sealing bars are sensitive against canting in the piston groove.

In the constructions with multi-partite sealing bars, a better gas tightness is assured; however, these sealing bars are gas-untight at the separating place. The consequence thereof is that initially very small soot lines form on the casing running surface or at the lateral surface of the lateral part which become noticeable later on as wear steps.

The present invention is concerned with the task to eliminate the aforementioned shortcomings in an advantageous manner by simple means.

The underlying problems are solved according to the present invention in that at least two sealing bars arranged in the piston have mutually different structures as regards their construction and/or the materials utilized in connection therewith.

According to the present invention, at least one of the several sealing bars arranged in the piston is constructed unitary or multi-partite.

The different types of sealing bars in one and the same piston offer the particular advantage that, for example, the disadvantages resulting from the multipartite construction of a sealing bar are compensated by the advantages of a unitary sealing bar.

In a preferred embodiment of the present invention, the sealing bars may be provided with at least one corner part mounted laterally at the sealing bar. It is thereby appropriate that the sealing bar consists of a main part and of at least one corner part whose plane surface facing the main part extends from the groove bottom up to the lateral part shortly underneath the sealing bar top.

However, in order to counteract such sealing bars whose main part extending over the entire piston width has a tendency to dig in into the lateral part with the small lateral surface thereof thereby forming ditchshaped grooves in the lateral part, the present invention provides in an advantageous embodiment that the flat surface facing the main part of the sealing bar of at least one comer part extends from the groove bottom to the sealing bar top whereby the distance from the separating plane to the lateral part in the upper area is smaller than in the lower area.

Advantageous is also the application of a sealing bar which consists of a trapezoidally shaped center part whose shorter side of the two parallel sides is constructed as sealing bar top or head portion, and of two corner pans laterally abutting at the center part.

This sealing bar exhibits a favorable lateral gas tightness with slight digging-in or running-in appearances at the lateral parts and smaller longitudinal wear because the lateral abutment pressure is specifically smaller.

According to the present invention, the sealing bar is also suited for a good lateral gas tightness which includes separating planes between the corner parts and the center part that are arranged at an angle to one another in such a manner that the surfaces of the center part and of the corner parts abut against one another only within the upper area of the sealing bar.

In order to obtain optimum running properties, an improvement of the surface quality of the sealing bar and of the casing running surface, a lesser wear at the sealing bar, fewer residues at the casing running surface and a better oil adherence at the sealing bar and casing running surface, the present invention additionally provides that the unitary and/or multi-partite sealing bars arranged in the same piston are made from mutually different materials.

According to the present invention; at least one of the sealing bars which are arranged in the piston as unitary or one-piece sealing bars, may consist of a different material.

As further advantageous feature of the present invention, the main or center part of at least one sealing bar may consist of a different material than the corner part.

Accordingly, it is an object of the present invention to provide a rotary piston internal combustion engine with sealing bars which avoid the aforementioned shortcomings and drawbacks encountered in the prior art.

Another object of the present invention resides in a sealing bar construction for rotary piston internal combustion engines which fully satisfies present-day requirements as regards gas tightness, particularly lateral gas tightness while at the same time minimizing its sensitivity against any canting in the piston groove.

A further object of the present invention resides in a rotary piston internal combustion engine with unitary or multi-partite sealing bars which minimizes the premature wear and improves the oil adherence at the sealing bar and at the running surface of .the casing.

These and other objects, features and advantages of the present invention will 'become more apparent from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, several embodiments in accordance with the present invention, and wherein:

FIG. 1 is an elevational view of a one-piece or unitary sealing bar in accordance with the present invention;

FIGS. 2 and 3 are elevational views of two embodiments of a two-partite sealing bar in accordance with the present invention; and

FIGS. 4 7 are elevational views of four further embodiments of three-partite sealing bars of different constructions in accordance with the present invention.

FIG. 8 is an elevational view of a modification of FIGS. 4 and 5 in accordance with the present invention. V

FIG. 9 is a sectional view of a rotary piston showing the arrangement of sealing bars therein in accordance with the present invention.

FIG. 10 is a sectional view taken along line 10l0 of FIG. 9 which shows the general arrangement of the sealing bars within the piston grooves in accordance with the present invention.

Referring now to the drawing wherein like reference numerals refer throughout to the various used-alike elements, the present invention relates to a conventional rotary piston internal combustion engine with a housing consisting of lateral parts 17 and 18, a casing 19 and a piston 20 that is provided with grooves 21 extending parallel to the piston axis over the entire piston width. Grooves 21 are each provided with a radial seal 1 in the form of one or several unitary or multi-partite sealing bars which are inserted in a radially movable manner.

The pairing of the sealing bars illustrated in FIGS. 1 to 7 in a piston, for example, in a triangular piston of a rotary piston internal combustion engine must take place in such a manner that the sealing bars positively influence one another by reason of their differing properties in order to reduce thereby the disadvantages of each individual unitary or multi-partite sealing bar to a minimum.

For example, the installation of only one ceramic unitary sealing bar 1 according to FIG. 1, may considerably improve the operating properties and operating behavior of the other sealing bars in the same piston made of different material and/or different construction.

Sealing bars can be utilized which consist of a main part 2 or 3 and of a corner part 4 or 5 according to FIGS. 2 and 3, respectively, whereby the main part 2 of the sealing bar illustrated in FIG. 1 extends over the entire piston groove length and slides with its lateral small surface 6 as well as with the corner part 4 laterally abutting at the main part 2 along a lateral part of the rotary piston internal combustion engine. The separating plane is so located that it has an angle of about 45 to about 60 as viewed in the longitudinal direction of the sealing bar.

The main part 3 and the corner part 5 of the sealing bar according to FIG. 3 are arranged in a similar manner to one another, only with the considerable difference that the main part 3 does not extend over the entire piston width, i.e., the surface 7 of the corner part 5 constructed as sealing bar top slides together with the sealing bar top of the main part 3 along the running surface of the casing.

The two-partite sealing bars according to FIGS. 2 and 3 may also be provided with two corner parts 8 and 9 arranged laterally at the main part 2 and 3 as is illustrated in FIGS. 4 and 5.

The sealing bars illustrated in FIGS. 6 and 7 are constructed three-partite whereby a center part 10 according to FIG. 6 has the shape of a trapezoid whose shorter one of the two parallel sides is constructed as sealing bar top or head portion and whose longer side is provided with a recess 1 1 which is provided for the accommodation and support of a second sealing bar spring. A corner part 12 is disposed laterally of the center part 10 on each side thereof.

The sealing bar according to FIG. 7 consists also of a center part 13 whose side facing the groove bottom of the piston is provided with a recess 14 required for the same purpose. The separating planes between the center part 13 and the corner parts 15, however, in contrast to the last-described sealing bar, are arranged at an angle to one another in such a manner that only the surfaces 16 of the corner parts and of the center part 13 disposed in the upper area of the sealing bar abut against one another.

It was customary heretofore to install in a piston radial sealing bars of same shape and same material. The

material pairing of the sealing bar top and of the running surface layer as well as of the sealing bar flank and piston groove can never be optimum because different material pairings necessarily present are subjected to different types of running and wear conditions. Furthermore, the lubricant temperatures and sliding conditions at the sealing bar top and flank are different.

By the use of sealing bar materials of different properties within the same piston, the sealing bars can exert with the correct selection as regards their type of construction and their material, an extraordinarily favorable infiuence on the adjacent sealing bars.

For example, the following different types of materials may be utilized for sealing bars in a piston:

l. Ceramic material together with cast iron.

2. Silicon nitride together with cast iron or chromium oxide.

3. Sintered materials together with cast iron.

4. Conventional hard metal together with cast iron.

5. Ceramic materials together with sintered materials.

With multi-partite sealing bars, depending on the requirements, also the outwardly disposed corner parts may be made from a different material than the main part or center part thereof.

Of course, the corner parts of the center bars illustrated in FIGS. 4 or 5 may be interchanged with one another whereby a sealing bar at one end includes a corner part 8 and at the other end a corner part 9.

Assuming a triangular piston is a rotary piston internal combustion engine, the following are typical applications of the present invention.

1. One unitary sealing bar for example, as shown in FIG. 1 is used in the groove of one piston corner while one multi-partite sealing bar each is used in the grooves of the other two piston corners.

2. One unitary sealing bar each as shown, for example, in FIG. 1 is used in each three piston grooves, though at least one sealing bar is made from different material.

3. One multi-partite sealing bar is used in one piston groove while one unitary sealing bar is used in each of the other two grooves.

While two sealing .bars in each groove of a piston corner the following typical possibilities exist.

4. Two multi-partite sealing bars are arranged in each of two piston groove while one unitary and one multipartite sealing bar is used in the third piston groove.

5. Two multi-partite sealing bars are used in each of two piston grooves while two unitary sealing bars are used in the third piston groove.

6. One unitary and one multi-partite sealing bar are arranged in each of the three grooves, whereby at least some or all of the unitary and/or multi-partite sealing bars may be made of different materials and/or the multi-partite sealing bars may be of different construction.

7. Two similar or different multi-partite sealing bars are used in one piston groove while one unitary and one multi-partite sealing bar are used in each of the other two piston grooves.

8. Two unitary sealing bars are used in one piston groove, two similar or different multi-partite sealing bars are used in a second piston groove while one unitary and one multi-partite sealing bar are used in the third piston groove.

Of course it is understood that in the examples 4-8 above, more than two sealing bars may be accommodated in a respective piston groove.

Furthermore, in examples 1 and 4-8 the same or different multi-partite sealing bars may be used, e.g., any one or more of the multi-partite sealing parts shown in FIGS. 2-7 of this application. Moreover, in lieu of or in addition thereto the differences between individual sealing bars can be achieved in any one of examples 1 and 3-8 above, by the use of different materials.

If, for example, in examples 4 or 5 above, a sealing bar as shown in FIG. 2 or FIG. 4 is followed by a sealing bar as shown in FIG. 3 or FIG. 5, then the scratches or grooves cut into the respective surfaces of the housing by the edges constituted by the separating joints of the different parts, will be counteracted by reason of their different physical location in a given bar, taking into consideration that a continuous (uninterrupted) surface of a following bar will seek to smooth out the groove-cutting tendency of the edges of the preceding bar or bars. Similar results can be achieved by the use of different materials.

While we have shown and described several embodiments in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art, and we, therefore, do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

What we claim is:

1. A rotary piston internal combustion engine with a housing including lateral parts and a casing and with a piston having a piston axis which piston is provided with several piston grooves extending substantially parallel to the axis over substantially the entire piston width, into which grooves radial sealing bar means are radially movably inserted, characterized in that at least one of said sealing bar means is multi-partite and consists of a center part and two corner parts, at least one of said corner parts includes plural adjacent surfaces extending at an angle to one another to define upper and lower corner part separating planes, said central part has at least one end which includes plural adjacent surfaces extending at an angle to one another to define upper and lower central part separating planes, each of said corner part separating planes faces a corresponding central part separating plane, and said central part abuts said at least one corner part only at the respective upper separating planes.

2. Sealing bar means for a rotary piston machine of the type having a housing including lateral parts and a casing and with a rotary piston having a plurality of axially extending piston grooves spaced about the periphery thereof, said sealing bar means being provided in each of said piston grooves and comprising at least one multi-partite sealing bar means having a main part with at least a first set of adjacent main-part separating planes extending at an angle to one another, said at least one multi-partite sealing bar means also having at least one corner part with adjacent corner-part separating planes extending at an angle to one another, said mainpart separating planes facing said corner-part separating planes in such a manner that only one of said at least first set of adjacent main-part separating planes abuts only one of said adjacent corner-part separating planes.

3. Sealing bar means according to claim 2, further comprising a plurality of said multi-partite sealing bar means.

4. A sealing bar means machine according to claim 2, wherein at least the main part of at least one sealing bar means consists of a material different from the respective corner part.

5. A sealing bar means machine according to claim 2, wherein at least two sealing bar means are different as regards both construction and material used therewith.

6. A sealing bar means machine according to claim 5, wherein at least one of the sealing bar means arranged in the piston is constructed in one piece.

7. A sealing bar means according to claim 2, wherein at least one sealing bar means is made of one-piece in the piston and is made from a different material than the other sealing bar means. 

1. A rotary piston internal combustion engine with a housing including lateral parts and a casing and with a piston having a piston axis which piston is provided with several piston grooves extending substantially parallel to the axis over substantially the entire piston width, into which grooves radial sealing bar means are radially movably inserted, characterized in that at least one of said sealing bar means is multi-partite and consists of a center part and two corner parts, at least one of said corner parts includes plural adjacent surfaces extending at an angle to one another to define upper and lower corner part separating planes, said central part has at least one end which includes plural adjacent surfaces extending at an angle to one another to define upper and lower central part separating planes, each of said corner part separating planes faces a corresponding central part separating plane, and said central part abuts said at least one corner part only at the respective upper separating planes.
 2. Sealing bar means for a rotary piston machine of the type having a housing including lateral parts and a casing and with a rotary piston having a plurality of axially extending piston grooves spaced about the periphery thereof, said sealing bar means being provided in each of said piston grooves and comprising at least one multi-partite sealing bar means having a main part with at least a first set of adjacent main-part separating planes extending at an angle to one another, said at least one multi-partite sealing bar means also having at least one corner part with adjacent corner-part separating planes extending at an angle to one another, said main-part separating planes facing said corner-part separating planes in such a manner that only one of said at least first set of adjacent main-part separating planes abuts only one of said adjacent corner-part separating planes.
 3. Sealing bar means according to claim 2, further comprising a plurality of said multi-partite sealing bar means.
 4. A sealing bar means machine according to claim 2, wherein at least the main part of at least one sealing bar means consists of a material different from the respective corner part.
 5. A sealing bar means machine according to claim 2, wherein at least two sealing bar means are different as regards both construction and material used therewith.
 6. A sealing bar means machine according to claim 5, wherein at least one of the sealing bar means arranged in the piston is constructed in one piece.
 7. A sealing bar means according to claim 2, wherein at least one sealing bar means is made of one-piece in the piston and is made from a different material than the other sealing bar means. 